This invention generally relates to a socket for a pin grid array package and, particularly, to an improved actuating mechanism for the socket.
Sockets are provided for a pin grid array (PGA) package such as a semi-conductor integrated circuit package in which lead pins are provided in a grid array. A typical socket includes a planar base housing provided with a plurality of terminals which can be electrically engaged with the lead pins of the PGA package. A planar slide member or plate is disposed on an upper side of the base housing and is provided with a plurality of through-holes in a grid array and through which the lead pins can be inserted. In some instances, a cover member may be provided on top of the slide plate, and through-holes also are provided in the cover member. Examples of such sockets are shown in Japanese Patent Laid-Open Publication No. Hei 7-142134 and Japanese Utility Model Registration No. 253644.
The slide plate for the socket described above allows the lead pins to be inserted into the socket with a zero insertion force when the slide plate is in a first or open position. After the lead pins are inserted through the slide plate, the plate is slidably moved relative to the base housing to a second or engagement position whereat the lead pins are brought into electrical connection with the terminals mounted on the base housing. Typically, some form of actuating mechanism is provided, operatively associated between the base housing and the slide plate, for moving the slide plate between its first and second positions.
One type of actuating mechanism according to the prior art is an eccentric shaft which is basically in the form of a screw member which is operated by an appropriate tool, such as a screwdriver. The screw member is axially fixed to the base housing but is rotatable relative thereto. The screw member has an eccentric portion engageable with the slide plate. Therefore, upon rotation of the screw member, the eccentric portion thereof moves the slide plate relative to the base housing between its first or open position and its second or engagement position. Although this type of actuating mechanism has proven quite effective, it creates a problem in requiring an operator to have a tool in order to use the socket.
Another type of actuating mechanism according to the prior art is a lever or operating handle rotatably mounted to the base housing. Like the rotatable screw member, the lever or handle has an eccentric or cam shaft for engaging the slide plate and moving the slide plate relative to the base housing. Again, such lever-type operating mechanisms have proven effective for their intended purposes, but they create problems in that they may be difficult to grasp, prone to breakage and require considerable vertical space for operation.
The present invention is directed to solving these problems by providing a low profile actuating mechanism which is simple to operate and requires no tools.
An object, therefore, of the invention is to provide a new and improved socket for a pin grid array (PGA) package having a plurality of lead pins in a grid array.
Another object of the invention is to provide an improved operating or actuating mechanism for such sockets.
In the exemplary embodiment of the invention, the socket includes a base housing and a plurality of terminals mounted on the base housing in a grid array corresponding to the grid array of the lead pins of the PGA package. A slide plate is mounted on the base housing and includes a plurality of through-holes arranged in a grid array for receiving therethrough the lead pins of the PGA package. The slide plate is slidably movable relative to the base housing in a given direction to drive the lead pins of the PGA package into engagement with the terminals on the base housing. A slide actuator is mounted on the base housing for sliding movement relative thereto in a direction generally transversely of the given direction of sliding movement of the slide plate. Complementary interengaging cam structure is provided between the slide plate and the slide actuator for slidably moving the slide plate relative to the base housing in response to sliding movement of the actuator relative to the housing.
As disclosed herein, the complementary interengaging cam structure includes a cam slot on one of the slide plate or slide actuator for receiving a cam follower on the other of the slide plate or slide actuator. The cam slot extends oblique to the given direction of sliding movement of the slide plate. In the preferred embodiment, the cam slot is on the slide actuator and the cam follower comprises a pin on the slide plate inserted into the cam slot. It also is contemplated that the cam slot includes a land area at least at one end thereof and extending generally perpendicular to the given direction of sliding movement of the slide plate. This land area prevents the cam follower from migrating along the cam slot once the slide plate is in its intended position. Preferably, one of the land areas is provided at both opposite ends of the cam slot.
Another feature of the invention is the provision of complementary interengaging detent structure between the slide actuator and the base housing to hold the actuator in at least one of its open or closed positions. Preferably, the detent structure is provided for holding the actuator in either of its open or closed positions. The detent structure also provides a tactile and audible indication of the actuator reaching either of its positions.
Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.